As air travel has increased over the past decades, airport facilities have become more crowded and congested. Minimizing the time between the arrival of an aircraft and its departure to maintain an airline's flight schedule, and also to make a gate or parking location available without delay to an incoming aircraft, has become a high priority in the management of airport ground operations. The safe and efficient ground movement of a large number of aircraft simultaneously into and out of ramp and gates areas has become increasingly important. As airline fuel costs and safety concerns and regulations have increased, the airline industry is beginning to acknowledge that continuing to use an aircraft's main engines to move aircraft during ground operations is no longer the best option. The delays, costs, and other challenges to timely and efficient aircraft pushback from airport terminals associated with the use of tugs and tow vehicles makes this type of aircraft ground movement an unattractive alternative to the use of an aircraft's main engines to move an aircraft on the ground. Restricted use of an aircraft's engines on low power during arrival at or departure from a gate is an additional, although problematic, option. Not only does such engine use consume fuel, it is also burns fuel inefficiently and produces engine exhaust that contains microparticles and other products of incomplete combustion. Operating aircraft engines, moreover, are noisy, and the associated safety hazards of jet blast and engine ingestion in congested gate and ramp areas are significant concerns that cannot be overlooked.
The use of a drive means, such as a motor structure, integrally mounted with a wheel to rotate the wheel of an aircraft has been proposed. The use of such a structure should move an aircraft independently and efficiently on the ground without reliance on the aircraft's main engines. U.S. Pat. No. 2,430,163 to Dever; U.S. Pat. No. 3,977,631 to Jenny; U.S. Pat. No. 7,226,018 to Sullivan; and U.S. Pat. No. 7,445,178 to McCoskey et al describe various drive means and motors intended to drive aircraft during ground operations. None of the foregoing patents, however, suggests a monitoring system that could be used with the described motor structures or other drive means to ensure efficient, reliable aircraft ground movement without reliance on an aircraft's engines.
U.S. Pat. No. 7,469,858 to Edelson; U.S. Pat. No. 7,891,609 to Cox; U.S. Pat. No. 7,975,960 to Cox; U.S. Pat. No. 8,109,463 to Cox et al; and British Patent No. 2457144, owned in common with the present invention, describe aircraft drive systems that use electric drive motors to power aircraft wheels and move an aircraft on the ground without reliance on aircraft main engines or external vehicles. While the drive means described in these patents and applications can efficiently and reliably move an aircraft autonomously during ground operations, the use of monitoring systems in conjunction with these drive means is not suggested.
None of the foregoing art, moreover, recognizes the significant improvements in drive means operating efficiency possible when roller-type traction or other drive systems are employed to actuate the drive means described to be capable of moving aircraft on the ground or when such systems are monitored to ensure their effective reliable performance during ground operations.
Sensors and monitors for aircraft and other vehicle wheels are known in the art. U.S. Patent Publication No. US2005/0046558 to Buenz et al, for example, describes a sensing system, primarily for sensing tire pressure, that may be modified to provide and/or include wheel speed sensing. In U.S. Pat. No. 8,186,403 to Sonzala et al, bearing or brake failure in a vehicle wheel is monitored with heat sensitive pressure barriers. Sensors effective for monitoring selected operating parameters and/or performance indicators in a roller traction drive-actuated drive means in an aircraft drive wheel that moves an aircraft autonomously during ground operations are not suggested, however.